Mechanisms of taste reception and synaptic transmission in vertebrate taste buds will be studied using the cutaneous taste epithelium of catfish as a model system. Intracellular recording and dye-marking techniques will be used to measure the passive membrane properties and stimulus-evoked responses of taste bud cells, in the skin of the catfish (Hoplosternum spp.), and mark the cells for electron microscopic identification. This procedure will permit correlations to be made between functional and morphological (light, dark, and basal) cell types within the taste bud. Using in situ barbels and isolated pieces of taste bud-containing skin, an attempt will be made to determine if stimulus-evoked changes in potential in taste cells are causally related to changes in firing in the gustatory neurons, by recording simultaneously from a taste bud cell and one of the nerve fibers innervating it. In addition, the possibilities of electrotonic coupling between taste bud cells and efferent control of taste cells will be examined. The mechanism of transmission at the taste receptor synapse will be studied using isolated-perfused barbels of the channel catfish (Ictalurus punctatus). Spontaneous and stimulus-evoked activity in the gustatory neurons supplying the barbel will be recorded before and after specific synaptic blocking agents and putative transmitters have been added to the perfusate. These experiments will lead to a better understanding of taste receptor mechanisms and the synaptic organization of the vertebrate taste bud.